The present invention relates to direct adhesion of materials and, more particularly, to improving the adhesion of a film of a material to a semiconductor by irradiating the interface between the surfaces with high energy ions.
Though the invention is of general application in its ability to enhance the adhesion of any conductor or semiconductor to any conductor or semiconductor substrate, there are many semiconductor substrates that do not form stable, adherent bonds even with pretreatment of the surface. Metal films applied to these surfaces by evaporation sometimes form weakly adherent bonds that can be readily peeled off the surface. Furthermore, it is difficult to reliably apply these metal films to semiconductors in a manner resulting in a low resistance contact.
There are many applications where the service life of the device is severely limited by the non-permanence of the interfacial bond between a metal film and a semi-conductor. For example, many small and intricately shaped devices such as the contacts to solid state lasers used for coupling to optical fiber communication cables are difficult to coat and present techniques are not amenable to forming very narrow electrodes of the order of 1000 Angstroms or less that are solderable. Other products currently being produced and/or developed that require bonding of a thin film of metal to a semiconductor substrate are semiconductor junctions and other semiconductor devices such as photovoltaic cells.